Frequencies for first 10,000 rows of endoint variable in nhamcsed2006 dataset :

endotrachea |
          l |
 intubation |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,973       99.73       99.73
        yes |         27        0.27      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016